Drier drainage system with pressure differential control



Dec. 14, 1954 H. 'G. CRAM 2,696,679

DRIER DRAINAGE SYSTEM WITH PRESSURE DIFFERENTIAL CONTROL Filed Jan. 21. 1953 s Sheets-Sheet 1 INVENTOR HERVEY G.CRAM

ATTORNEYS H. G. CRAM Dec. 14, 1954 DRIER DRAINAGE SYSTEM WITH PRESSURE DIFFERENTIAL CONTROL 3 Sheets-Sheet 2 Filed Jan. 21. 1953 INVENTOR HERVEY G. CRAM ATTORNEYS H. G. CRAM 2,596,679

DRIER DRAINAGE SYSTEM WITH PRESSURE DIFFERENTIAL CONTROL Dec. 14, 1954 3 Sheets-Sheet 3 Filed Jan. 21. 1955 INVENTOR HERVEY G.CRAM

ATTORNEYS United States Patent G DRIER DRAINAGE SSTEM PRESSURE DIFFERENTIAL. CQNTROL Hervey G.- Cram, Appleton, Wis...

Application January 21, .1953, Serial No. 352,139

8 Claims; (61; 34 -419)- This invention. appertainst-broadly'toheating, and drain-- ing systems for paper dryers of. the general type. shown.

in certain of my. priorpatents, such-.asRatents No; b919,-

4l6;,No. 2,045,634 andNo. 2,242,778'issued respectively on July 25, 1933;;June 30,1936. and May-:20, 194 1.

Oneof the primary; objects of thepresent inventionis to efiect an improvement. in the efliciency of, steamefilled" rotating cylindrical; dryers, over. which and: in; contact; with,.a continuous sheet of material, such as,,paper-, is.

passing for the purpose of'drying,

Steamis delivered totheindividual cylindrical dryer through the dryer journal tothe interior-cfor contactwithi the shell of the dryer where the latentand otherheat of.

thesteam is transferred to: and throughthe shell of tthe less than that of the metal of .thedryer shell;

Air and other non+condensable gaseswith which-the steam is more orless contaminated, .must also be removed or. maintained at: the very lowest minimum. accumulation possible, as a concentration.- atthe interiorsurface of the dryer shell, or even as a mixture with the steam, is-- very detrimental to the rate of drying, in that the rate of conductivity of heat throughair is greatly less than that of cast iron.

The most feasible method ofremoving the condensate from the dryer, is-through the dryer journaLwith a-vertical siphon dropleg pipe. (see my prior patents abovementioned), having an. open inlet in close proximity to the dryer shelll Theonly knownmethodvof maintaining a minimum accumulation of'air and othernon-condensable gases in a dryer during operation is by means of a continuous circulation of'the steam. through the dryer, and thereby, carrying the air and other non-condensable gases along with it, and the simplest method of accomplishing this purpose, .is by ejecting afixed minimum amount of steam along with the condensatethrough the siphon. I

Based on the above, another. salient object'ofmy invention is the provision of..means for the re-using of the latent and other heatof this steam in certain of the drying cylinders of abattery of cylindrical dryers. v

A further object ofthe invention is to providein a battery of cylindrical dryers, a primary section receiving its steam from the usual source ofsupply anda secondary section receiving its steam from the discharge of the dryers of the primarysection, the arrangement being such as to create an eflFective pressure; differential across the dryers of the primary sectionwhich is suflicient to lift the condensate up the .verticalLdrop leg ofIthe siphon, to and through the dryer journal, and, to circularize the steam through the dryer. I

A further important-objector my invention is to effect a pressure ditferentialacross the dryers of the secondary section by means. of a condenser, and/ or, a vacuum pump, and to maintain a fixed ahydrostatic head of condensate on the intake of the pump, plus the steam pressure in thedischarge line from .the'dryers, and thereby adding to pump efliciency.

A still. further object of my invention. is to regulate the flow ofv steam as.discharged withthe condensate from the primary. section accordingto thedemand of the secondary section and thedemand of .the condenser, vand/ or,

the vacuum pump, and to establish and maintainaut'oe matically the fixedpredetermined pressure differential across each individual dryer for. this purpose.

A-still further important object of my invention is m provide-a continuous suction effect'on the siphon of each dryer, so' that as soonas the inlet of a siphon iscon-,

densate-sealed, discharge fromthe. dryer. willbe immedi-.

atelyefiected, thereby assuringa minimum accumulation of condensate in each dryer.

A. still further important object" of my invention is to provide means. forvisible. observation oflthe rate of-fiow of condensate and steam beingdischarged' fromeach' individualdryenso that such rate ofldischarge can be accuj rately determined; I

A stillrfur-ther important object of the invention .is'the provision of la novelivalve arrangement in'the discharge portion for each dryer to establish and maintain automatically the desired,. fixed pressure difierential across each individual dryer.v

With these and other ohjects' in view, the inventio'ri consists in the. novelconstruction, arrangement watermation of parts,.as. will be hereinafter more: specifically. described and claimed, and illustrated in" the acco pany" ing drawings, in whichdrawing's, v

v Figure l is a'diagrammaticview in'sid'elevation',.sh"oW- ing my improved system incorporated with' a'battery'of dryers in a paper making machine.

Figure 2' is an enIargedIragmentarydetailview through' a portion of a dryer showingthes'iphonfin the dryer jo'urnal, the parts in=sectionbeing taken on the line 2-2 of Figure 3 lookingin the direction of the arrows;

Figure 3 is an end elevational viewof a portion of a dryer with parts the'reofi'broken away and in section and illustrating, thepressure differential valvecasing incorporated in' the dischargelin'e or leg' ofthe dryer;

Figure 4' is an enlarged detail vertical sectional view taken on theline' 44ofiFigure2 lookingin'th'e'direc tion of the arrows illustratingthe" novelpre'ssure' differential valve. I v

Figure 5 isa horizontal sectional viewthrough the direction ofthe arrows.

Figure 6 is'a detail iside elevationalview of'the'novel' valve body employed in'the valve. 2

Referring tov the drawingsindetailj and more pfarticue larly to'Figure 1, I'h'ave" shownldia'grammaticallya bat tery. B-of dryers'of a papefmakin'g'machine, andthese dryers'areof' the rotating, cylindrical ty'pe; over which and in contact with which a-continuous sheet of paper (not shown) is passingjfor the purpose of'dryin'g;

In; accordance with my invention, the battery B of dryers is: divided into a"primarysection'ldof' a'ny'nunn ber of cylindrical dryers andia secondary 'section 11 co'mposed of. a plurality of dryers; The" secondary section; 11 for the purposeof illustration; includes two dryers I12 and '13 and a'bab'y' dryer 1'4.

Steam is supplied to'" the primary section 1'0thr'ough" a header 15* and this'header' isfed with stearn from'a' supplyline'16'leading-froma suitable source not shown); Each of the dryers of the primary section 10 anfd the secondary section" 11 is provided withia hollow journal 17, and the outer"endsfofall of these journals are provided withcoupjlin'gs 18. Connected with the'couplings' 18' of the dryers :of'theprimary section 10' are feederfpi'pe's" 19, branching ,ofl oftheheader 15. Connected with the' couplings 18' of'thedryersof the seconda y: section-11 are' feeder pipes 20,,which" will belater-referred tb;

The water of condensation and'air and other non condensable' gases 'frorn'the' various dryers'of the'p'rinra'ry. and secondary sections 10and111; are'removed hy'siphons 21 (see'my'patent'No; 2,617,205;issuedNovember: 11, 1952). Each siphon 21" includes" a' horizontal section" 22 which extends through the steam joint or coupling 18' and'the inneri'siphon or drop leg23. Thelower end of Jthe siphon leg 23 isprovid'ed'with the inlethea'd 24; Extended along the batteryyB ofr'drying' cylinders is" a condensateheaderZS; .an'dcoupled with this hea'der'are the'outer siphon legs 26 forf the dryers of thepjrimary' section 10 andthe outer legs 26 are coupled with the horizontal section j 22 of the" siphons for" the primary section. The-horizontal section 22of the siphons 2 1 for the dryers of the section 11 have coupled therewith outer legs 27. These legs 27 are all connected with a secondary header 28 for condensate. The feeder pipes 20 for the dryers of the secondary section 11 are all connected with the main condensate header 25.

Briefly, from the description so far, steam is supplied to the dryers of the primary section from the header and the condensate and gases are removed from these dryers to the header 25, and this header, in turn,

supplies the dryers of the secondary section 11 with steam for heating these dryers and the condensate and gases from the dryers of the secondary section 11 are removed by the siphons of these dryers and delivered to the secondary header 28 for condensate. Thus, heat from the steam removed from the dryers of the primary section is utilized again for heating the dryers of the secondary section and this forms an important feature of my invention.

As brought out in the objects of this specification, one of the main features is to create an effective pressure differential across the dryers of the primary section 1'3, so as to lift the condensate up the vertical drop leg 23 of each dryer in the primary section and to circularize the steam through each dryer and to regulate the flow of steam as discharged with the condensate from the primary section to the demand of the secondary section and to establish and maintain automatically a fixed predetermined pressure ditferential across each dryer. This is essential, in that, drying conditions are continuously changing owing to the variations in the sheet being dried, such as, moisture content, weight of the sheet, etc.

In order to accomplish these purposes, I provide in each outer drop leg 26 of the dryers of the primary section 10, and each outer drop leg 27 of the dryers of the secondary section 11, a pressure differential control valve 29, and this valve is best shown in Figures 4, 5 and 6, and will now be described in detail.

Each valve 29 includes a casing 30, preferably formed in an upper section 31 and a lower section 32 for ease in manufacture and assembly, and these sections 31 and 32 are united in fluid tight relation by bolts 33. Formed in the casing is an inner valve chamber 34 provided at its lower end with a valve seat 35 forming an inlet and at its upper end with an outlet opening 36. Communicating with the valve seat 35, is an outer passageway 37 into which flows the condensate and make-up steam. Communicating with the opening 36 is an outer passageway 38, which leads to the discharge section of the outer drop leg. Directly above the opening 36 in the valve chamber 34 is an orifice 39 formed in the interior division wall of the passageways 37 and 38, and this orifice is also disposed directly below the inlet of the casing 30 for the condensate and make-up steam.

Slidable and rotatable within the valve chamber 34 is a valve body 40 and formed on the valve body are radially extending vertical guide ribs 41, which space the valve body proper from the wall of the valve chamber 34. The lower end of the valve body is tapered, as at 42, for fitting snugly on the valve seat 35, when the valve is in its closed position. The lower ends of the guide ribs 41 are tapered or beveled on one side, as at 43, and water of condensate impinging on the faces 43 tends to turn the valve body for the purpose of insuring the seating of the valve body and to increase the noticeability of the body when viewed through a sight glass 45 carried by one side of the valve casing 30. The provision of this sight glass not only enables an observer to view the functioning of the valve body but to also visibly determine the flow of condensate through the valve casing.

This pressure differential control valve 29 functions as follows: condensate, surplus steam, air and other noncondensable gases are delivered through the siphon inlet 24 to and through the siphon drop leg 23 and through the dryer journal for discharge through pipes 26 and 27, as the case may be, to the pressure differential control valve 29.

Delivery from the pipe is to the passageway 37 and the flow therein is in the direction of the arrows as indicated on Figure 4 vertically through the valve seat 35 at a rate of flow as determined by the position of the valve body 40 with relation to the valve seat 35; thence past the valve body 40 through the opening 36 and through passageway 38 to the discharge pipe. 7

The valve body 40 operates through gravity and a predetermined pressure differential across the valve seat 35 is fixed by the weight of the valve body 40, in rela' tion to the area of the valve seat 35; it being understood that the valve body 40 is of a predetermined, definite mass. The purpose of the bypass orifice 39 is to by-pass the valve body 40 with a constant fixed rate of flow of steam, or a mixture of steam and water for the double purpose of: (1) to maintain a constant circulation of steam through the dryer for the eviction of air and other non-condensable gases, and (2), to provide a continuous suction effect on the siphon inlet 24, so that, immediately the inlet 24 is condensate-sealed, ejection of the condensate is effected even though the valve body 46) may be in the closed position.

A further advantage, is that, with the valve body 40, in a closed position, the flow of condensate as elfected by the by-pass orifice 39 will cause the condensate to build up in passageway 37 and the pipe with sufficient head pressure, which is additional to the pressure differential across the dryer, to lift the valve body 441" for discharge of the condensate.

As the prime purpose of the invention is to operate on a battery of dryers, and this means, that a multiplicity of pressure differential control valves 29 are operating individually to control the pressure differential between the steam header and the condensate header serving the battery, therefore, a slight variation in the operation of an individual control valve 29 could result in a valve being in a closed position, however, this can only be temporary, as the flow of condensate as induced by the by-pass orifice 39 will force the lifting of the valve body 40 in a matter of seconds.

The main condensate header 2:? is connected by a drain pipe 46 to the inlet of a rotary discharge or like pump 47, and the outlet of this pump has connected therewith a discharge pipe 48 which leads back to the boiler plant. The secondary condensate header 2% enters into a uni-rate condenser 49, the outlet of which is connected by a pipe 50 to the drain pipe 46 adjacent to the inlet of the pump 47. Cooling water may be supplied to the uni-rate condenser 49 through a pipe 52. Air and other non-condensable gases and a very small amount of steam is discharged from the top of the uni-rate condenser 49 through a pipe 52 to a desired vacuum chamber or pump.

A by-pass pipe 53 is provided across the pump 4'7 2037} pipe 48 to pipe 46. The purpose of this pipe 53 is to by-pass sufiicient condensate across the pump 41 to maintain a fixed level of condensate in the pipe, 45, as shown by the dotted line indicated by the reference character 54, and this means, (1) a constant condensate head 54 in the pipe 46 plus the pressure in the condensate header 25, which provides the effective head in the intake of the pump 47; (2), a constant condensate head in the pipe 50, as indicated by the dot and dash line number 55, equal to the condensate head 54 in the pipe 45, plus the pressure differential across the dryers 12 and 13 and the baby dryer 14 as fixed by the pressure differential control valves 29.

An automatic liquid level controller 56 is provided for the by-pass pipe 53 and a control valve 57 is incorporated in the length of the by-pass pipe and is actuated automatically by the liquid level controller 56. The oppos te ends of the controller are connected respectively to the pipe 46 above the head level 54 and to the by-pass pipe between the control valve 57 and the pipe 54.

From the foregoing description it can be seen that I have provided a novel heating and draining system for a battery of dryers which the latent heat in the stream is utilized to its fullest extent and in which a definite control is provided for each dryer of the battery of dryers.

Changes in details may be made without departing from the spirit or the scope of this invention, but what 1 claim as new is:

l. In a paper making machine, a battery of dryers including a primary section of dryers and a secondary section of dryers, means for circulating steam through the dryers of the primary section including a header for steam, means connecting all of the dryers of the primary section with the header, a header for condensate and returning steam for all of the dryers of the primary section, and a siphon for each of the dryers of the prisection including an outer drop leg pipe connected with the header for condensate and returning steam, and automatic means for maintaining a fixed predetermined pressure across each dryer of the primary section including a gravity operated valve of a predetermined mass in the drop leg pipe of each siphon.

2. In a paper making machine, as defined in claim 1, and means for by-passing each valve for maintaining a constant minimum rate of flow of steam through the drop leg pipe of each siphon.

3. In a paper making machine, a battery of dryers including a primary section of dryers and a secondary section of dryers, means for circulating steam through the dryers of the primary section including a header for steam, means connecting all of the dryers of the primary section to the header, a header for condensation and returning steam for all the dryers of the primary section, a siphon for each of the dryers of the primary section connected with the header for condensation, and means for circulating steam and condensate from the last mentioned header to the dryers of the secondary section, means for removing condensate from the dryers of the secondary section, and automatic means for maintaining a fixed predetermined pressure difierential across each dryer including a gravity operated valve of a predetermined mass.

4. In a paper making machine, a battery of dryers including a primary section of dryers and a secondary section of dryers, means for circulating steam through the dryers of the primary section including a header for steam, means connecting all of the dryers of the primary section with the header, a header for condensate and returning steam for all of the dryers of the primary section, a siphon for each of the dryers of the primary section including an outer drop leg pipe connected with the header for condensate and steam, means connecting all of the dryers of the primary section with the header for condensate and returning steam, a siphon for each of the dryers of the primary section for withdrawing condensate from said dryers and each including an outer drop leg pipe, a secondary header for condensate for said last mentioned drop leg pipe, and means disposed in the length of all of said drop leg pipes for the dryers of the primary and secondary sections for automatically maintaining a fixed predetermined pressure differential across each dryer, and said last named means including a casing having communication at its opposite ends with sections of the outer drop leg pipes, a valve chamber in said casing including a lower valve seat and an upper escape port, a gravity operated valve of a predetermined mass slidable in the chamber for controlling flow of condensate vertically through the valve seat, and said casing having a passageway communicating with an upper section of pipe of the outer drop leg and valve seat and an outer passageway communicating with the escape port and a lower section of the outer drop leg pipe.

5. In a paper making machine as defined in claim 4, and means for bypassing the valve body for maintaining a constant minimum rate of flow of steam through the drop leg pipe of each siphon.

6. In a paper making machine as defined in claim 4, and means for by-passing the valve body for maintaining a constant minimum rate of flow of steam through the drop leg of each siphon and said last named means including a communication between the passageways directly above the escape port of the valve chamber.

7. In a paper making machine as defined in claim 4, and a sight glass carried by said casing in proximity to the valve chamber whereby the action of the valve body and the flow of condensate can be observed.

8. In a paper making machine as defined in claim 4, and a sight glass in said casing in proximity to the valve chamber whereby the action of the valve body and the fiow of condensate can be observed, and means on said valve body against which the condensate impinges for turning said valve body.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,704,436 Jennings Mar. 5, 1929 1,817,110 Stickle Aug. 4, 1931 2,049,050 Cram July 28, 1936 2,094,038 Kernin Sept. 28, 1937 

